// d3.tip
// Copyright (c) 2013 Justin Palmer
//
// Tooltips for d3.js SVG visualizations

(function (root, factory) {
    'use strict';
    if (typeof define === 'function' && define.amd) {
        // AMD. Register as an anonymous module with d3 as a dependency.
        define(['d3'], factory);
    } else if (typeof module === 'object' && module.exports) {
        // CommonJS
        module.exports = function(d3) {
            d3.tip = factory(d3);
            return d3.tip;
        };
    } else {
        // Browser global.
        root.d3.tip = factory(root.d3);
    }
}(this, function (d3) {
    // Public - contructs a new tooltip
    //
    // Returns a tip
    'use strict';
    return function() {
        var direction = d3_tip_direction,
            offset    = d3_tip_offset,
            html      = d3_tip_html,
            node      = initNode(),
            svg       = null,
            point     = null,
            target    = null;

        function tip(vis) {
            svg = getSVGNode(vis);
            point = svg.createSVGPoint();
            document.body.appendChild(node);
        }

        // Public - show the tooltip on the screen
        //
        // Returns a tip
        tip.show = function() {
            var args = Array.prototype.slice.call(arguments);
            if(args[args.length - 1] instanceof SVGElement) { target = args.pop(); }

            var content = html.apply(this, args),
                poffset = offset.apply(this, args),
                dir     = direction.apply(this, args),
                nodel   = getNodeEl(),
                i       = directions.length,
                coords,
                scrollTop  = document.documentElement.scrollTop || document.body.scrollTop,
                scrollLeft = document.documentElement.scrollLeft || document.body.scrollLeft;

            nodel.html(content)
                .style({ opacity: 1, 'pointer-events': 'all' });

            while(i--) { nodel.classed(directions[i], false); }
            coords = direction_callbacks.get(dir).apply(this);
            nodel.classed(dir, true).style({
                top: (coords.top +  poffset[0]) + scrollTop + 'px',
                left: (coords.left + poffset[1]) + scrollLeft + 'px'
            });

            return tip;
        };

        // Public - hide the tooltip
        //
        // Returns a tip
        tip.hide = function() {
            var nodel = getNodeEl();
            nodel.style({ opacity: 0, 'pointer-events': 'none' });
            return tip;
        };

        // Public: Proxy attr calls to the d3 tip container.  Sets or gets attribute value.
        //
        // n - name of the attribute
        // v - value of the attribute
        //
        // Returns tip or attribute value
        tip.attr = function(n, v) {
            // jshint unused:false
            if (arguments.length < 2 && typeof n === 'string') {
                return getNodeEl().attr(n);
            } else {
                var args =  Array.prototype.slice.call(arguments);
                d3.selection.prototype.attr.apply(getNodeEl(), args);
            }

            return tip ;
        };

        // Public: Proxy style calls to the d3 tip container.  Sets or gets a style value.
        //
        // n - name of the property
        // v - value of the property
        //
        // Returns tip or style property value
        tip.style = function(n, v) {
            // jshint unused:false
            if (arguments.length < 2 && typeof n === 'string') {
                return getNodeEl().style(n);
            } else {
                var args =  Array.prototype.slice.call(arguments);
                d3.selection.prototype.style.apply(getNodeEl(), args);
            }

            return tip;
        };

        // Public: Set or get the direction of the tooltip
        //
        // v - One of n(north), s(south), e(east), or w(west), nw(northwest),
        //     sw(southwest), ne(northeast) or se(southeast)
        //
        // Returns tip or direction
        tip.direction = function(v) {
            if (!arguments.length) { return direction; }
            direction = v == null ? v : d3.functor(v);

            return tip;
        };

        // Public: Sets or gets the offset of the tip
        //
        // v - Array of [x, y] offset
        //
        // Returns offset or
        tip.offset = function(v) {
            if (!arguments.length) { return offset; }
            offset = v == null ? v : d3.functor(v);

            return tip;
        };

        // Public: sets or gets the html value of the tooltip
        //
        // v - String value of the tip
        //
        // Returns html value or tip
        tip.html = function(v) {
            if (!arguments.length) { return html; }
            html = v == null ? v : d3.functor(v);

            return tip;
        };

        // Public: destroys the tooltip and removes it from the DOM
        //
        // Returns a tip
        tip.destroy = function() {
            if(node) {
                getNodeEl().remove();
                node = null;
            }
            return tip;
        };

        function d3_tip_direction() { return 'n'; }
        function d3_tip_offset() { return [0, 0]; }
        function d3_tip_html() { return ' '; }

        var direction_callbacks = d3.map({
                n:  direction_n,
                s:  direction_s,
                e:  direction_e,
                w:  direction_w,
                nw: direction_nw,
                ne: direction_ne,
                sw: direction_sw,
                se: direction_se
            }),

            directions = direction_callbacks.keys();

        function direction_n() {
            var bbox = getScreenBBox();
            return {
                top:  bbox.n.y - node.offsetHeight,
                left: bbox.n.x - node.offsetWidth / 2
            };
        }

        function direction_s() {
            var bbox = getScreenBBox();
            return {
                top:  bbox.s.y,
                left: bbox.s.x - node.offsetWidth / 2
            };
        }

        function direction_e() {
            var bbox = getScreenBBox();
            return {
                top:  bbox.e.y - node.offsetHeight / 2,
                left: bbox.e.x
            };
        }

        function direction_w() {
            var bbox = getScreenBBox();
            return {
                top:  bbox.w.y - node.offsetHeight / 2,
                left: bbox.w.x - node.offsetWidth
            };
        }

        function direction_nw() {
            var bbox = getScreenBBox();
            return {
                top:  bbox.nw.y - node.offsetHeight,
                left: bbox.nw.x - node.offsetWidth
            };
        }

        function direction_ne() {
            var bbox = getScreenBBox();
            return {
                top:  bbox.ne.y - node.offsetHeight,
                left: bbox.ne.x
            };
        }

        function direction_sw() {
            var bbox = getScreenBBox();
            return {
                top:  bbox.sw.y,
                left: bbox.sw.x - node.offsetWidth
            };
        }

        function direction_se() {
            var bbox = getScreenBBox();
            return {
                top:  bbox.se.y,
                left: bbox.e.x
            };
        }

        function initNode() {
            var node = d3.select(document.createElement('div'));
            node.style({
                position: 'absolute',
                top: 0,
                opacity: 0,
                'pointer-events': 'none',
                'box-sizing': 'border-box'
            });

            return node.node();
        }

        function getSVGNode(el) {
            el = el.node();
            if(el.tagName.toLowerCase() === 'svg') {
                return el;
            }             

            return el.ownerSVGElement;
        }

        function getNodeEl() {
            if(node === null) {
                node = initNode();
                // re-add node to DOM
                document.body.appendChild(node);
            }
            return d3.select(node);
        }

        // Private - gets the screen coordinates of a shape
        //
        // Given a shape on the screen, will return an SVGPoint for the directions
        // n(north), s(south), e(east), w(west), ne(northeast), se(southeast), nw(northwest),
        // sw(southwest).
        //
        //    +-+-+
        //    |   |
        //    +   +
        //    |   |
        //    +-+-+
        //
        // Returns an Object {n, s, e, w, nw, sw, ne, se}
        function getScreenBBox() {
            var targetel   = target || d3.event.target;

            while ('undefined' === typeof targetel.getScreenCTM && 'undefined' === targetel.parentNode) {
                targetel = targetel.parentNode;
            }

            var bbox       = {},
                matrix     = targetel.getScreenCTM(),
                tbbox      = targetel.getBBox(),
                width      = tbbox.width,
                height     = tbbox.height,
                x          = tbbox.x,
                y          = tbbox.y;

            point.x = x;
            point.y = y;
            bbox.nw = point.matrixTransform(matrix);
            point.x += width;
            bbox.ne = point.matrixTransform(matrix);
            point.y += height;
            bbox.se = point.matrixTransform(matrix);
            point.x -= width;
            bbox.sw = point.matrixTransform(matrix);
            point.y -= height / 2;
            bbox.w  = point.matrixTransform(matrix);
            point.x += width;
            bbox.e = point.matrixTransform(matrix);
            point.x -= width / 2;
            point.y -= height / 2;
            bbox.n = point.matrixTransform(matrix);
            point.y += height;
            bbox.s = point.matrixTransform(matrix);

            return bbox;
        }

        return tip;
    };

}));
